The objective of this research was to determine colour changing proporties of sodium hydroxide + hydrogen peroxide, sodium hydroxide + calcium hydroxide + hydrogen peroxide, hypochlorite and hydrochloric acid applied on the pine (Pinus silvestris l), oriental beech (Fagus orientalis libsky), ash wood (Fraxinus excelsior l.) and oak (Quercus petraea spp), The second steps of research was to determine colour changing effects of acrylic, synthetic, polyurethane and acid catalized varnishes on the bleached wood samples. Results indicated that sodium hydroxide + hydrogen peroxide and sodium hydroxide + calcium hydroxide+hydrogen peroxide chemicals are strong bleaches, hypochlorite and hydrochloric acid chemicals are weak bleaches, acrylic and synthetic varnishes gave the lightest colour but polyurethane and acid hardener varnishes gave the darker colour.

The objective of this research was to determine colour changing proporties of sodium hydroxide + hydrogen peroxide, sodium hydroxide + calcium hydroxide + hydrogen peroxide, hypochlorite and hydrochloric acid applied on the pine (Pinus silvestris l), oriental beech (Fagus orientalis libsky), ash wood (Fraxinus excelsior l.) and oak (Quercus petraea spp), The second steps of research was to determine colour changing effects of acrylic, synthetic, polyurethane and acid catalized varnishes on the bleached wood samples. Results indicated that sodium hydroxide + hydrogen peroxide and sodium hydroxide + calcium hydroxide+hydrogen peroxide chemicals are strong bleaches, hypochlorite and hydrochloric acid chemicals are weak bleaches, acrylic and synthetic varnishes gave the lightest colour but polyurethane and acid hardener varnishes gave the darker colour.